In a semiconductor device, a metal such as titanium (Ti) or the like is employed as, e.g., a wiring material, and also, a metallic silicide is used for reducing a parasitic resistance of a MOS transistor or the like. For example, in a MOS transistor manufacturing process, after a Ti film is formed on a gate electrode or a surface of a diffusion layer, it is silicided by heat-treatment and the unreacted Ti film is removed. As a technology for removing the Ti film formed on the substrate by an etching, there has been proposed a method for performing a dry etching by using a plasma of a CF4 based etching gas (see, e.g., references 1 and 2).                Reference 1: Japanese Patent Laid-open Application No. S53-118372 (e.g., FIGS. 1 to 5)        Reference 2: Japanese Patent Laid-open Application No. S56-66040 (e.g., the claims)        
In general, a high etching rate is preferable to improve a throughput and, even in case of a Ti film etching, a processing is required to be performed at a high etching rate. However, the aforementioned conventional technologies are totally silent on increasing the etching rate. For example, in the method of Reference 2, only an etching rate of about 30˜40 nm/min is obtained, even though the etching is carried out after a pre-etching for a rapid start has been performed (see, FIG. 1 of reference 2). Hence, it cannot possibly response a recent high speed etching.
Meanwhile, in case when an etching is performed on the Ti film at a high rate by using a plasma of a CF based gas as described in the aforementioned References 1 and 2, a re-deposition of an etching residue, so-called a fence, may be generated. Such a phenomenon means that the etching residue such as Ti or the like is scattered due to a strong sputtering during the high speed etching to be deposited again on a photoresist or a side of other metal material. Since the fence causes a Ti contamination, it needs to be avoided as possible.
Further, while the Ti film is plasma etched, a large amount of deposits are produced in the chamber. These deposits cause a particle contamination, thereby hampering the fabrication of the reliable semiconductor device. Accordingly, it is necessary to consider a counter measure for the deposits in the chamber during the plasma etching of the Ti film.